A biosphere was the total area on a planet where life existed. It could also be an artificial self-contained environment.
The Kromon could build giant biospheres, thanks to having stolen the technology, along with the philosophy of management, from a company that exploited the planet Kromon. The Eutermesans were enslaved by the Kromon and set to work as slaves in their biospheres. After the Kromon royals died, causing the rest of the Kromon to become motionless and directionless, the Eutermesans returned to their home towns and villages. (AUDIO: The Creed of the Kromon)